Maryland - The U.S. government has bought 195 million doses of H1N1 swine flu vaccine for a possible autumn vaccination campaign, a U.S. federal official said Thursday.

The U.S. Health and Human Services Department has also contracted for 120 million doses of adjuvant, a compound to stretch the number of doses of vaccine needed, the department's Dr. Robin Robinson told a meeting of Food and Drug Administration advisers.

Five companies are making H1N1 vaccine for the U.S. market -- AstraZeneca's MedImmune unit, Australia's CSL Ltd, GlaxoSmithKline Plc, Novartis AG and Sanofi-Aventis SA.

Earlier, an FDA official said vaccine makers were only getting about 30 percent as much vaccine from eggs as they usually get with seasonal influenza vaccine.

Robinson said HHS had accounted for this in planning for a possible influenza pandemic.

We thought manufacturers would probably get a low or poor yield. That has been borne out, Robinson told the meeting.

He said HHS had planned to have 160 million doses available right away, and then 80 million a month afterward. It would take until March at this rate to vaccinate the full U.S. population of 300 million people with two doses each, Robinson said.

The five vaccine-making companies will tell the FDA committee later Thursday about what they have learned as they work with the virus, which spread globally in less than two months.

World Health Organization and U.S. health officials have said they want to start vaccinating people against H1N1, alongside regular seasonal flu, in October. The FDA has to approve this vaccine before it can be used but FDA officials indicated earlier Thursday they would like to speed this process.

(Editing by Mohammad Zargham)